This investigation is concerned with the determination of the mechanical mechanisms governing in-sity solute transport into articular cartilage. The mobility of various solutes of different size and charge will be followed utilizing radioactively tagged molecules. The direct measurement of the rate of solute transport, the concentration of solute and the depth of solute penetration, as well as the dependency of these parameters upon the concentration of the solute profusion solution, load configuration and tissue structure, will be performed and analyzed. Uncharged molecules, ranging in size from 20 to 250,000 MW, and two small charged molecules will be transported into unload and cyclically loaded articular cartilage for 1, 5, 10 and 15 minutes, and for 24 hours. The tissue will be quick-frozen, sliced into 100 micron thick sections, desorbed and counted. Characteristic curves of concentration versus depth will then be obtained. Theoretical models and non-linear regression curve fits will provide a characteristic diffusion coefficient. Equilibrium times will provide a characteristic partition coefficient. These parameters will be determined for normal tissue and tissue which has been altered by removal of the uppermost articular layer, degradation of the proteoglycan matrix and degradation of the collagen framework. The results from this study will provide an understanding of the mechanisms responsible for nutrient transport and joint lubrication in the normal and pathological state. In addition, it will provide needed information for themethodologies necessary in the detection and treatment of degenerative joint disease.